Sherlock Holmes

Murder in the castle...
Sherlock Holmes investigates about a murder that occured more than 10 years ago.
Duke of Densmore was killed by the explosion of a bomb hidden in an armour in his bedroom.
The testament also destroyed by this explosion, was said to damage one of his 7 ex-wives.
However he had invited each of them in the castle at some time, for a few days.
As the bomb was adjusted to fit in the armour, the murderess came in the castle several times.
Each of them, interviewed by Holmes, swears that she went there only once.
No one remembers, ten years after, the exact time when she went there.
Holmes asks about who they met there :